This invention relates to a contactor for mass transfer between two phases, and is particularly concerned with a continuous liquid/liquid or solids/liquid contactor comprising a vesel through which the phases pass and in which buckets within the vessel promote intermingling of the phases.
A contactor of the type referred to has been described for liquid/liquid contacting in British Pat. No. 972,035 and, for solids/liquid contacting, in U.S. Pat. No. 3,649,209. In each, the buckets are of approximately semi-cylindrical form and are carried between radial partition discs, dividing the interior into a series of compartments. The buckets are located adjacent the peripheries of the discs, and, in each compartment, there are a number of buckets which are spaced apart around the axis of rotation of the rotor constituted by the discs and buckets.
In operation of the known contactor, the two phases are passed through the vessel, preferably in counter-current, while the rotor is turned gently. A nominally stable interface is formed between the two phases at approximately the horizontal plane passing through the axis of rotation. In practice, however, it has been found that the passage of the distinct buckets through the interface and their wakes break up the interface and entrain in each liquid phase minute particles or bubbles of the other phase. Because of their size, the minute bubbles do not migrate readily, if at all, back to the parent phase and are carried out of the contactor vessel with the other phase. The distinct buckets and the rods which bridge successive discs and which are shown in the U.S. patent specification further create vortices in the two phases, again resulting in the generation of particles which settle only with difficulty.